Intertidal Habitats Research Articles

Combining Multispectral and Radar Imagery with Machine Learning Techniques to Map Intertidal Habitats for Migratory Shorebirds

Migratory shorebirds are notable consumers of benthic invertebrates on intertidal sediments. The distribution and abundance of shorebirds will strongly depend on their prey and on landscape and sediment features such as mud and surface water content, topography, and the presence of ecosystem engineers. An understanding of shorebird distribution and ecology thus requires knowledge of the various habitat types which may be distinguished in intertidal areas. Here, we combine Sentinel-1 and Sentinel-2 imagery and a digital elevation model (DEM), using machine learning techniques to map intertidal habitat types of importance to migratory shorebirds and their benthic prey. We do this on the third most important non-breeding area for migratory shorebirds in the East Atlantic Flyway, in the Bijagós Archipelago in West Africa. Using pixel-level random forests, we successfully mapped rocks, shell beds, and macroalgae and distinguished between areas of bare sediment and areas occupied by fiddler crabs, an ecosystem engineer that promotes significant bioturbation on intertidal flats. We also classified two sediment types (sandy and mixed) within the bare sediment and fiddler crab areas, according to their mud content. The overall classification accuracy was 82%, and the Kappa Coefficient was 73%. The most important predictors were elevation, the Sentinel-2-derived water and moisture indexes, and Sentinel-1 VH band. The association of Sentinel-2 with Sentinel-1 and a DEM produced the best results compared to the models without these variables. This map provides an overall picture of the composition of the intertidal habitats in a site of international importance for migratory shorebirds. Most of the intertidal flats of the Bijagós Archipelago are covered by bare sandy sediments (59%), and ca. 22% is occupied by fiddler crabs. This likely has significant implications for the spatial arrangement of the shorebird and benthic invertebrate communities due to the ecosystem engineering by the fiddler crabs, which promotes two vastly different intertidal species assemblages. This large-scale mapping provides an important product for the future monitoring of this high biodiversity area, particularly for ecological research related to the distribution and feeding ecology of the shorebirds and their prey. Such information is key from a conservation and management perspective. By delivering a successful and comprehensive mapping workflow, we contribute to the filling of the current knowledge gap on the application of remote sensing and machine learning techniques within intertidal areas, which are among the most challenging environments to map using remote sensing techniques.

Use of a multi-metric macroalgal index to document severe eutrophication in a New Zealand estuary

ABSTRACT Environmental indicators that reliably describe estuary trophic response to nutrient loading are required for the effective management of New Zealand estuaries. A common estuary eutrophication response is frequent, extensive and persistent opportunistic macroalgae blooms. This study explores the utility of the Opportunistic Macroalgal Blooming Tool (OMBT) in the New River Estuary (∼4600 ha), a shallow intertidal-dominated system within a pastoral farming catchment in Southland, New Zealand. Total nitrogen (TN) loads increased from 3206 T y−1 in 2000 to 5143 T y−1 in 2020. Concomitantly, areas of opportunistic macroalgae, measured using the OMBT, expanded across the available intertidal habitat (AIH) from 34.9 ha or 1.4% of the AIH to 1383 ha or 47.6% of the AIH, and the average wet weight biomass increased from 19.3 g m−2 to a peak of 1326 g m−2 in 2019. We hypothesise that opportunistic macroalgae expanded rapidly in direct response to temporal increases in TN load, with increases disproportionately contributed by expansion and intensification of dairy farming in the catchment. This study confirmed that the OMBT predictably responded to changes in TN concentration and may therefore be useful in defining estuary-specific TN concentration thresholds to inform likely load reductions required to achieve improved environmental outcomes.

Estuaries as coastal reactors: importance of shallow seafloor habitats for primary productivity and nutrient transformation, and impacts of sea level rise

ABSTRACT Estuaries are hotspots of primary productivity and nutrient transformation that contribute to food webs and ecosystem functioning locally and in adjacent ecosystems. The depth-dependence of nutrient transformation and primary productivity rates in the water column and the seafloor were investigated, and the lateral transport of solutes and materials across the estuary mouth were quantified. Using an estuary dominated by shallow soft-sediment habitats as a case study, the effects of sea level rise (SLR) on productivity and nutrient transformation processes were projected. The estuary was a net importer of dissolved nutrients from the coast, and a net exporter of suspended sediments and chlorophyll a, supporting the notion that estuaries are important nutrient transformation reactors. A significant depth (and light) effect on productivity indicates that increasing stressors associated with climate change that reduce light at the seafloor (SLR and increased turbidity) will negatively impact estuarine productivity. Intertidal and shallow subtidal benthic habitats were responsible for most of the productivity of the estuary and this is likely to be consistent for other shallow estuaries globally. SLR and anthropogenic intervention that prevents landward migration (i.e. seawalls and armouring), will result in the loss of these habitats and their significant contributions to adjacent coastal ecosystems.

Factors that affect migratory Western Atlantic red knots (Calidris canutus rufa) and their prey during spring stagingon Virginia's barrier islands.

Understanding factors that influence a species' distribution and abundance across the annual cycle is required for range-wide conservation. Thousands of imperiled red knots (Calidris cantus rufa) stop on Virginia's barrier islands each year to replenish fat during spring migration. We investigated the variation in red knot presence and flock size, the effects of prey on this variation, and factors influencing prey abundance on Virginia's barrier islands. We counted red knots and collected potential prey samples at randomly selected sites from 2007-2018 during a two-week period during early and peak migration. Core samples contained crustaceans (Orders Amphipoda and Calanoida), blue mussels (Mytilus edulis), coquina clams (Donax variabilis), and miscellaneous prey (horseshoe crab eggs (Limulus polyphemus), angel wing clams (Cyrtopleura costata), and other organisms (e.g., insect larvae, snails, worms)). Estimated red knot peak counts in Virginia during 21-27 May were highest in 2012 (11,959) and lowest in 2014 (2,857; 12-year peak migration [Formula: see text] = 7,175, SD = 2,869). Red knot and prey numbers varied across sampling periods and substrates (i.e., peat and sand). Red knots generally used sites with more prey. Miscellaneous prey ([Formula: see text] = 2401.00/m2, SE = 169.16) influenced red knot presence at a site early in migration, when we only sampled on peat banks. Coquina clams ([Formula: see text] = 1383.54/m2, SE = 125.32) and blue mussels ([Formula: see text] = 777.91/m2, SE = 259.31) affected red knot presence at a site during peak migration, when we sampled both substrates. Few relationships between prey and red knot flock size existed, suggesting that other unmeasured factors determined red knot numbers at occupied sites. Tide and mean daily water temperature affected prey abundance. Maximizing the diversity, availability, and abundance of prey for red knots on barrier islands requires management that encourages the presence of both sand and peat bank intertidal habitats.

Seaweed Habitats on the Shore: Characterization through Hyperspectral UAV Imagery and Field Sampling

Intertidal macroalgal habitats are major components of temperate coastal ecosystems. Their distribution was studied using field sampling and hyperspectral remote mapping on a rocky shore of Porspoder (western Brittany, France). Covers of both dominating macroalgae and the sessile fauna were characterized in situ at low tide in 24 sampling spots, according to four bathymetric levels. A zone of ca. 17,000 m2 was characterized using a drone equipped with a hyperspectral camera. Macroalgae were identified by image processing using two classification methods to assess the representativeness of spectral classes. Finally, a comparison of the remote imaging data to the field sampling data was conducted. Seven seaweed classes were distinguished by hyperspectral pictures, including five different species of Fucales. The maximum likelihood (MLC) and spectral angle mapper (SAM) were both trained using image-derived spectra. MLC was more accurate to classify the main dominating species (Overall Accuracy (OA) 95.1%) than SAM (OA 87.9%) at a site scale. However, at sampling points scale, the results depend on the bathymetric level. This study evidenced the efficiency and accuracy of hyperspectral remote sensing to evaluate the distribution of dominating intertidal seaweed species and the potential for a combined field/remote approach to assess the ecological state of macroalgal communities.

The estuarine plastics budget: A conceptual model and meta-analysis of microplastic abundance in estuarine systems

Rivers and estuaries are a key transport pathway for microplastics to enter the world's oceans. Despite this, knowledge of the fate of plastic debris in estuaries is limited. Our study assesses the current state of knowledge on the distribution of microplastic debris in estuaries and their intertidal habitats. The literature is reviewed, and an estuarine plastics conceptual model is presented. The conceptual model is populated with data to show the globally averaged standing stocks of microplastic (<5 mm) debris in estuarine waters and sediments. Estuarine plastic debris studies have previously focused on subtidal sediment and surface waters more than intertidal habitats. Estimated mean microplastic abundance is found to be greater (H = 53.136, P = 0.000175) per volume of sediment than per volume of water, although there are large standard deviations within habitats and some caveats regarding variation in methods and limited data in published studies. We found that the most commonly recovered microplastics align with the most commonly used polymers, and that the rates of microplastic transfer between estuarine compartments remain poorly understood. This study informs global plastic transport models by demonstrating the ability of estuaries to trap large quantities of microplastic debris, but substantial differences in the methodologies between estuarine microplastic studies limit the value of global assessments of estuarine microplastics. The main recommendations from this study focus on improving data availability and standardisation to better enable study comparisons and to improve our ability to examine global trends.

Remote Sensing of Coastal Vegetation Phenology in a Cold Temperate Intertidal System: Implications for Classification of Coastal Habitats

Intertidal vegetation provides important ecological functions, such as food and shelter for wildlife and ecological services with increased coastline protection from erosion. In cold temperate and subarctic environments, the short growing season has a significant impact on the phenological response of the different vegetation types, which must be considered for their mapping using satellite remote sensing technologies. This study focuses on the effect of the phenology of vegetation in the intertidal ecosystems on remote sensing outputs. The studied sites were dominated by eelgrass (Zostera marina L.), saltmarsh cordgrass (Spartina alterniflora), creeping saltbush (Atriplex prostrata), macroalgae (Ascophyllum nodosum, and Fucus vesiculosus) attached to scattered boulders. In situ data were collected on ten occasions from May through October 2019 and included biophysical properties (e.g., leaf area index) and hyperspectral reflectance spectra (Rrs(λ)). The results indicate that even when substantial vegetation growth is observed, the variation in Rrs(λ) is not significant at the beginning of the growing season, limiting the spectral separability using multispectral imagery. The spectral separability between vegetation types was maximum at the beginning of the season (early June) when the vegetation had not reached its maximum growth. Seasonal time series of the normalized difference vegetation index (NDVI) values were derived from multispectral sensors (Sentinel-2 multispectral instrument (MSI) and PlanetScope) and were validated using in situ-derived NDVI. The results indicate that the phenology of intertidal vegetation can be monitored by satellite if the number of observations obtained at a low tide is sufficient, which helps to discriminate plant species and, therefore, the mapping of vegetation. The optimal period for vegetation mapping was September for the study area.

Occasional sexual reproduction significantly affects the population structure of the widespread, predominantly asexually reproducing marine worm Lineus sanguineus (Nemertea: Pilidiophora)

Asexual reproduction by fissiparity has only been described from very few of the approximately 1300 nemertean species that otherwise mainly reproduce sexually. The best studied fissiparous species, Lineus sanguineus (Rathke 1799), is a cosmopolitan heteronemertean species inhabiting intertidal habitats of temperate coasts. Although sexual reproduction has never been described, molecular data suggest that sexual reproduction substantially shapes the genetic structure of the investigated populations. In an attempt to clarify the extent of sexual reproduction, three gene fragments (COI, 16S, ITS) were sequenced for 108 specimens sampled in 8 European localities. The results of a phylogenetic analysis and haplotype network showed no clear distinction between different populations, thus indicating the presence of sexual reproduction. Furthermore, we provide circumstantial evidence for the presence of a comparably long-lived planktonic larval stage as present in the closest relatives of L. sanguineus. To further understand the impact of abiotic factors on sexual reproduction and fissiparity, the effect of different temperature and illumination regimes on reproductive behavior and fragmentation was studied in specimens from a population from Bergen, Norway that share the same haplotype. Experimental setups represented summer (long light period and elevated temperature) and winter (short light and decreased temperature) conditions. Under winter conditions, a higher number of animals remained sexually mature and at least one specimen shed eggs on one occasion. Thus, although short light and/or low temperatures are most likely the influential factors on sexual maturity, the factors that influence fissiparity are less clear. The results of this study further solidify the cosmopolitan status of L. sanguineus and clarify the population structuring of this species. In addition, the study provides first data on the dynamics of sexual and asexual reproduction modes on which future investigations will have to expand, especially regarding genetic and physiological aspects.

Understanding the consequences of sea level rise: the ecological implications of losing intertidal habitat

ABSTRACT Sea level rise (SLR) has been described as one of the greatest potential causes of ecosystem disruption, putting many coastal areas at risk of irreversible changes. However, the loss of intertidal areas from SLR and the associated ecological and social repercussions receive little attention. Within estuaries, extensive intertidal areas harbour a variety of habitats and communities and represent hotspots of ecosystem functions. Any changes to their distribution or extent are likely to have far reaching implications. Here we summarise the ecological consequences of a reduction in intertidal area from increasing SLR, and the implications for people, management and planning. To facilitate this discussion, changes in the occurrence and abundance of two ecologically and culturally important intertidal shellfish species (Austrovenus stutchburyi and Macomona liliana) were modelled under different SLR scenarios for Tauranga Harbour, Aotearoa New Zealand. We highlight how the squeezing of intertidal areas will likely alter the distribution and extent of key habitats and communities, and discuss the implications for coastal food webs, ecosystem functioning and service provision. Pre-emptive planning and adaptive management are needed that incorporate ecological losses in risk assessments and focuses on pro-active solutions to increase resilience to the effects of SLR.

Author Correction: Molluscs community as a keystone group for assessing the impact of urban sprawl at intertidal ecosystems

Author Correction: Molluscs community as a keystone group for assessing the impact of urban sprawl at intertidal ecosystems

Shoreline armor removal can restore variability in intertidal ecosystems

Humans have drastically modified marine nearshore ecosystems through shoreline armoring. Armor, in the form of seawalls and bulkheads, reduces the mean abundance of key ecological features of shoreline ecosystems, such as the amount of beach wrack, the number of beached logs, and the density of supratidal invertebrates. Armor also affects the physical and biological composition and diversity of these important ecological responses – altering the makeup of beach wrack and invertebrate species, for example. Less is known, however, about changes in variability – both over time and space – of ecological responses across natural, restored, and armored shores. Temporal and spatial variation in physical and biological variables can themselves be indicators of ecosystem health and effectiveness of restoration. Working alongside community (citizen) scientists, we found that beach wrack (a nutrient and habitat resource), logs (an element of habitat structure), and supratidal invertebrates (part of the consumer community) often increased following restoration. Further, not only were wrack, logs, and invertebrates on average more abundant and diverse at natural (never armored) shore types compared to armored shore types, but they also frequently had higher variance. In many cases, variance of ecological responses in restored shore types were more similar to natural shore types than armored shore types, indicating a positive effect of restoration. We found that differences among sample sites, rather than across sample years, explained more of the variation in ecological responses across all shore types. Because shoreline armoring is a pervasive human activity, public perception of this variability is key to the social context of restoration success. Participation in data collection through community science endeavors is one way to encourage an appreciation for natural variability within and across landscapes. We implore that shoreline monitoring efforts should evaluate and communicate ecosystem variability as a key indicator of restoration success.

Groundwater discharge locally shapes the rocky shore macroinvertebrate community in South-Southwest Portugal

Groundwater discharge is an essential process in the functioning of coastal aquatic ecosystems due to its significant role in nutrient cycling, geochemical mass balances and primary productivity. However, the occurrence patterns, importance, and effects of this discharge on rocky shores communities remain largely unknown. We assessed the importance of groundwater discharge into the highly ecologically important intertidal ecosystems. We compared the benthic macroinvertebrate composition and abundance between discharge and no-discharge sites, replicated for five shores in South and Southwest Portugal. This robust replicated feature across shores and regions is a particularly novel contribution to the field. Groundwater discharge significantly affected the biological communities’ abundance across all shores, but not biodiversity patterns. The algae Enteromorpha sp., snail Melaraphe neritoides and lichen Verrucaria maura can potentially be used as bioindication tools for shifts in groundwater discharge quantity and qualitative patterns. Our study validates the importance of this commonly overlooked local disturbance factor in regulating intertidal communities.

The genome of a mangrove plant, Avicennia marina, provides insights into adaptation to coastal intertidal habitats.

Whole-genome duplication, gene family and lineage-specific genes analysis based on high-quality genome reveal the adaptation mechanisms of Avicennia marina to coastal intertidal habitats. Mangrove plants grow in a complex habitat of coastal intertidal zones with high salinity, hypoxia, etc. Therefore, it is an interesting question how mangroves adapt to the unique intertidal environment. Here, we present a chromosome-level genome of the Avicennia marina, a typical true mangrove with a size of 480.43Mb, contig N50 of 11.33Mb and 30,956 annotated protein-coding genes. We identified 621 Avicennia-specific genes that are mainly related to flavonoid and lignin biosynthesis, auxin homeostasis and response to abiotic stimulus. We found that A. marina underwent a novel specific whole-genome duplication, which is in line with a brief era of global warming that occurred during the paleocene-eocene maximum. Comparative genomic and transcriptomic analyses outline the distinct evolution and sophisticated regulations of A. marina adaptation to the intertidal environments, including expansion of photosynthesis and oxidative phosphorylation gene families, unique genes and pathways for antibacterial, detoxifying antioxidant and reactive oxygen species scavenging. In addition, we also analyzed salt gland secretion-related genes, and those involved in the red bark-related flavonoid biosynthesis, while significant expansions of key genes such as NHX, 4CL, CHS and CHI. High-quality genomes in future investigations will facilitate the understand of evolution of mangrove and improve breeding.

Optimizing the Scale of Observation for Intertidal Habitat Classification through Multiscale Analysis

Monitoring intertidal habitats, such as oyster reefs, salt marshes, and mudflats, is logistically challenging and often cost- and time-intensive. Remote sensing platforms, such as unoccupied aircraft systems (UASs), present an alternative to traditional approaches that can quickly and inexpensively monitor coastal areas. Despite the advantages offered by remote sensing systems, challenges remain concerning the best practices to collect imagery to study these ecosystems. One such challenge is the range of spatial resolutions for imagery that is best suited for intertidal habitat monitoring. Very fine imagery requires more collection and processing times. However, coarser imagery may not capture the fine-scale patterns necessary to understand relevant ecological processes. This study took UAS imagery captured along the Gulf of Mexico coastline in Florida, USA, and resampled the derived orthomosaic and digital surface model to resolutions ranging from 3 to 31 cm, which correspond to the spatial resolutions achievable by other means (e.g., aerial photography and certain commercial satellites). A geographic object-based image analysis (GEOBIA) workflow was then applied to datasets at each resolution to classify mudflats, salt marshes, oyster reefs, and water. The GEOBIA process was conducted within R, making the workflow open-source. Classification accuracies were largely consistent across the resolutions, with overall accuracies ranging from 78% to 82%. The results indicate that for habitat mapping applications, very fine resolutions may not provide information that increases the discriminative power of the classification algorithm. Multiscale classifications were also conducted and produced higher accuracies than single-scale workflows, as well as a measure of uncertainty between classifications.

The effects of desiccation and salinity gradients on the PSII photochemical efficiency of an intertidal brown alga, Sargassum fusiforme from Kagoshima, Japan

SUMMARYThe responses of photochemical efficiency to desiccation and salinity gradients in an intertidal edible brown macroalga, Sargassum fusiforme (Harvey) Setchell (Sargassaceae, Fucales), were determined using a pulse amplitude modulation (PAM)‐chlorophyll fluorometer. The effective quantum yields (ΔF/Fm'; = ΦPSII) of photosystem II (PSII) dropped to zero after 360‐min aerial exposure under low irradiance (20 μmol photons m−2 s−1) and 120‐min exposure under high irradiance (700 μmol photons m−2 s−1) for this species at 20°C and 50% relative humidity. Under these conditions, ΔF/Fm' failed to recover to initial levels even after 1‐day rehydration in seawater. In general, ΔF/Fm' decreased as desiccation reduced the absolute water content (AWC, %). Nevertheless, when AWC was above ca. 20%, ΔF/Fm' was mostly restored to initial levels after 1‐day rehydration in seawater, suggesting strong tolerance to dehydration. Furthermore, S. fusiforme appeared to tolerate a broad range of salinity (i.e. 15–50 psu) during six days of culture; however, ΔF/Fm' declined when salinity was &lt;10 and 60 psu. Strong tolerance to dehydration and salinity stress likely provides S. fusiforme an advantage that allows it to flourish in the intertidal habitat.

A phenology-based vegetation index classification (PVC) algorithm for coastal salt marshes using Landsat 8 images

• Constructed a new CRVI for red vegetation extraction. • Proposed an enhanced semi-automatic PVC algorithm. • The optimal PVIs reflected the phenological differences of vegetation. • The developed classification model had spatio-temporal stability and scalability. Coastal salt marshes, as a globally significant intertidal ecosystem, are highly productive but extremely fragile and unstable. Mapping coastal salt marshes accurately is the basis of assessing global climate change, biological invasion, and coastal erosion. Using Landsat 8 images, this paper integrated the advantages of pixel- and phenology-based algorithms and vegetation indices in vegetation classification. An enhanced phenology-based vegetation index classification (PVC) algorithm is proposed to obtain the spatial distribution and community composition of coastal salt marshes in Bohai Sea of China accurately and quickly. The results showed that (1) the coastal redness vegetation index (CRVI) can be used to extract Suaeda spp. effectively, and the phenology-based vegetation indices (PVIs) dataset can alleviate the spatial variability of phenology in coastal salt marshes; (2) the crucial phenological periods for identifying coastal salt marshes are May, October, and November, and the optimal PVIs are consistent with the phenological characteristics of salt marshes; (3) during the year 2018–2019, the overall accuracy (OA) of the PVC algorithm in Yancheng coast of Jiangsu Province and Bohai Sea coast reached 80.49 % and 90.8 % respectively. A total of 14,763.39 ha of salt marshes were found in the coastal area of Bohai Sea, and Shandong Province had the most abundant types of salt marshes and the largest area; (4) the classification model based on the PVC algorithm is stable and scalable in 2016–2017 and 2020–2021, with the OA of 89.19% and 86.67% respectively. These results demonstrate the value of the PVC algorithm in vegetation classification, and this study can provide a referable semi-automatic vegetation classification method for other coastal areas.

DNA-barcoding reveals cryptic diversity and re-evaluation of Ocypode (family: Ocypodidae) from the Sundarbans - UNESCO World Heritage Centre

Crabs are one of the most diversified crustaceans among metazoans, from both morphological and ecological point of view. Among them, ghost crabs (Genus Ocypode; Family Ocypodidae) play an important role in the tropical and sub-tropical intertidal ecosystems. Due to a lack of comprehensive data, their cryptic behaviour, mimicry or camouflage, and a lack of formal taxonomic documentation, identification of this group is often difficult. Molecular taxonomy can help to overcome these barriers by assisting in species identification. The present study is the first large scale attempt to identify ghost crabs using DNA barcodes, which are now available globally, for 16 morphospecies in the genus Ocypode. A total of 164 barcodes were analysed for species delimitation that are available globally including specimens collected from the Indian Sundarbans. Various species delimitation methods (K2P, NJ, Bayesian supported PTP and Bayesian tree) revealed a total of 19 MOTUs for 16 distinct species where multiple MOTUs were observed in 3 species with inconsistencies in genetic distances and tree topologies. We recognised cryptic diversity in Ocypode macrocera, O. platytarsis and O. quadrata with intraspecies distances greater than the species delimitation threshold of 0.053 ± 0.01. The current study also concluded that O. platytarsis and O. brevicornis are two distinct species, putting an end to the debate over their species synonymy. Furthermore, our Bayesian analysis confirmed the retraction of the genus Hoplocypode specified only for O. occidentalis. As a result, the current research added a new dimension to ghost crab taxonomy by contributing to the detection of cryptic species, thus speculating the possibility of new species and reaffirming the effectiveness of the DNA barcoding while demanding enrichment of the global database for comprehensive species identification and extensive approach of molecular taxonomy as well as morphological interventions in solving taxonomic puzzles.

EFFECT OF TEXTURAL FEATURES FOR LANDCOVER CLASSIFICATION OF UAV MULTISPECTRAL IMAGERY OF A SALT MARSH RESTORATION SITE

Abstract. Salt marshes are intertidal ecosystems valuable for services including coastal protection and carbon sequestration. Restoration of salt marshes is popular in this era of climate change and sea-level rise, especially in areas where marshes have been historically altered, including in the Bay of Fundy. Salt marsh restoration involves landcover change through time as a community of halophytic vegetation develops in the study area. Restoration sites are difficult to survey using traditional on-foot methods, and developing remote sensing methods to survey them would increase efficiency of monitoring. The purpose of our study was to assess the capability of UAV multispectral imagery to map landcovers in a salt marsh restoration site in the Musquash Estuary, New Brunswick, Canada. We used the Random Forests (RF) supervised classifier and validated our maps using field data. We also evaluated the importance of textural features by running two classifications, with and without textural features. The classification omitting textural features had lower classification and validation accuracies (96.29 % and 91.23 %, respectively) than the classification and validation accuracies obtained by including textural features (99.56 % and 96.84 %, respectively). Additional work is required to test our method in different locations and seasons.

Intertidal beach habitat suitability model for Pacific sand lance (Ammodytes personatus) in the Salish Sea, Canada

Pacific sand lance ( Ammodytes personatus) support marine food webs in the Salish Sea, yet our knowledge of intertidal spawning habitat for this species is limited. Increasing participation in community science surveys for intertidal sand lance spawning has resulted in the detection of eggs on more than 90 beaches in the Canadian Salish Sea since 2001. Using these data, we developed a MaxEnt habitat suitability model using six environmental variables. We estimate that only 5.4% of the intertidal zone of the Canadian Salish Sea has a moderate to high likelihood of providing suitable sand lance spawning habitat. This rare habitat was best predicted by its proximity to estuaries, shoreline slope, distance to predicted subtidal sand lance burying habitat, seabed substrate, and aspect. Our model could be used as the basis for a Pacific coast-wide model in areas with less available information. Identifying intertidal spawning habitat of sand lance will support conservation efforts intended to maintain forage fish species.

Rhynchospioaciliata sp. nov., a new spionid species (Annelida, Spionidae) from the Korea Strait.

A new spionid polychaete, Rhynchospioaciliata sp. nov., was discovered in the fine sandy sediments of an intertidal habitat from Korean waters. The new species is considered a simultaneous hermaphrodite, but no brooding embryos were found in any of the specimens collected in this study. This species is unique in the absence of ciliation in the anteriormost chaetigers. Rhynchospioaciliata sp. nov. is morphologically most similar to Rhynchospiofoliosa Imajima, 1991 from Japan in having an elevation on the prostomium, conspicuously large and foliaceous branchiae, and intersegmental lateral pouches. However, the new species differs from the latter by the following characteristics: (1) large and lanceolate notopodial postchaetal lamellae of chaetiger 1, (2) transverse ciliated bands and ciliation on the inner branchiae absent in anteriormost chaetigers, and (3) pygidium with one pair of ventral cirri and numerous elongated dorsolateral cirri. Detailed description and illustrations of the new species are provided with molecular information on mitochondrial cytochrome c oxidase subunit I (COI), 16S ribosomal DNA (rDNA), nuclear 18S rDNA, and 28S rDNA.